You can hardly expect people to be kind and forgiving 100% of the time, messing up on thunderous once is OK, it happens sometimes. But doing it twice may get on some peoples nerves, TIF mod or not. You have to remember that while being for teaching, not all the members of DGS are there to teach, they are there to learn. You messing up on thunderous seems like you've not tried hard enough to learn how too. You can't get mad at someone shouting at you a little for messing up, if you do then I don't really think DGS is for you. Otherwise, suck it up, take it in your stride and strive to do better in the future.